Issue 638: Implementing .2 properties in RDF

The issue closely relates to Issue 588 (the policy for implementing .1 properties in RDF) and is affected by any decisions therein. It is listed as a separate issue, only to better keep track of things. 

The outcome of the present issue (and 588 of course) are expected to have a bearing on the reorganization of property definitions in CRMbase and extensions and should be taken into consideration upon redesigning the templates for CRM extensions (see here), but also the template used for CRMbase.  

Post by Pavlos Fafalios (2 May 2023)

Dear Gerald, all,

I think we can follow the same reification approach as we do for the .1 properties. 
In this case, we just need to provide the property classes of the domain and range properties of AP13.2, i.e.: 
    PC_AP13_has_stratigraphic_relation_to    
and   
    PC_AP11_has_physical_relation_to

Then, here is a (draft) example of RDF triples that make use of these constructs:
 
***********************************************************
<PC_AP13_has_stratigraphic_relation_to>
   a  <PC0_Typed_CRM_Property> .
<PC_AP11_has_physical_relation_to>
   a  <PC0_Typed_CRM_Property> .

<subject1> 
   <AP13_has_stratigraphic_relation_to> <object_1> .
<pc_ap13_instance> 
   a <PC_AP13_has_stratigraphic_relation_to> ;
   <P01_has_domain> <subject1> ;
   <P02_has_range> <object1> . 

<subject2> 
   <AP11_has_physical_relation_to> <object_2> .
<pc_ap11_instance> 
   a <PC_AP11_has_physical_relation_to  > ;
   <P01_has_domain> <subject2> ;
   <P02_has_range> <object2> . 

<pc_ap13_instance>
     <AP13.2 justified by> <pc_ap11_instance>
***********************************************************

But there are also other approaches for implementing this, such as using named graphs, or the standard RDF reification method (i.e. using rdf:subject, rdf:object, etc.), or RDF-start (I think). 

Please correct me if I have misunderstood something! 

Best regards,
Pavlos
 

Post by Pavlos Fafalios (2 May 2023)

Dear George,

About the PC constructs and, in general, if this is the best method to implement CRM's properties of properties in RDF (considering Francesco's email and arguments): I was not involved in the initial discussions, when the SIG first introduced the idea of property classes for implementing the
.1 properties of CRM (I see they were first introduced in Jan 2015 for crm version 6.0).

My suggestion is to first close issue 588 (since we have already voted for most of its sub-issues) and then open a new issue for discussing this aspect.

Thoughts?

Best,
Pavlos

Post by Martin Doerr (2 May 2023)

Dear George,

I agree that often links with properties simplify a more complex entity. There are complex questions of the philosophical distinction between relationships and the entities that exist by their own. E-R model and RDFS differ considerably in this respect. Regarding the question of "state", I think the use of the term itself suggests a simplicity that does not exist. We have discussed extensively concepts of state and situation, without coming to a clear unique definition of what it can mean. In the extreme, we can regard any property instance as a kind of "state".

I see the question more practical, to model all these intermediate things explicitly as distinct, in a proactive way,  would need a lot of effort, without a clear demand. Also, there is the question, where to stop the intermediate of the intermediate of the intermediate entity. With respect to the statigraphic relations below, I do not agree that there are hidden entities. Simply, I regard this "directed correspondence" construct to be of /epistemic /nature, and it is missing as primitive in the KR languages we use.

All the best,

Martin